Vapor-Liquid Equilibrium of Trioxane-Formaldehyde-Water-BMIMNO₃ System

The effects of ionic liquids BMIMNO₃ on the vapor-liquid equilibria of formaldehyde-trioxane-water（FA-TOX-H₂O） systems were studied. The results showed that adding BMIMNO₃ could effectively improve the vapor-liquid equilibrium of the system, and adding a certain amount of BMIMNO₃ could eliminate the azeotrope phenomenon. The non-random two-liquid (NRTL) model was used to fit the experimental data. The average relative deviation between experimental and calculated values of the TOX-H₂O-BMIMNO₃ ternary system was 1.32%, and that of the FA-H₂O-BMIMNO₃ ternary system was 1.74%. The vapor-liquid equilibrium of TOX-FA-H₂O-BMIMNO₃ was measured. The results showed that the addition of BMIMNO₃ could increase the molar fraction of TOX in the vapor phase by 17.49%. The results are significant for increasing the molar fraction of TOX in vapor phase.